It was a jolly good episode otherwise, but the bloody lengthy explanation and flashback to the fight were annoying. In the end its only purpose was to suddenly and without any solid reason explain Hisoka's techniques. That should have been left to a later time when Gon and Killua understand them. Besides, who cares about Kastro anymore, including the tiniest specifics of his defeat? Machi could have talked about the audience when she mused Hisoka will have forgotten Kastro's face by tomorrow.